Validation of prognostic models in elderly patients with diffuse large B-cell lymphoma in a real-world nationwide population-based study - development of a clinical nomogram.

The International Prognostic Index (IPI) is the most frequently used tool for prognostication in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) of all ages. This study validated and compared six models developed for patients above 60 with International Prognostic Indices (IPI, R-IPI, NCCN-IPI). Moreover, we created a clinical nomogram with an online tool for individualized predictions. A total of 2,835 patients aged over 60 with newly diagnosed DLBCL treated with potentially curative immunochemotherapy were identified in the Danish Lymphoma Registry. A nomogram was developed by combining NCCN-IPI variables (excluding extranodal localization), albumin, and platelet levels in 1,970 patients and verified the results in the remaining 956 patients. Compared to other models, the elderly IPI (E-IPI) and age-adjusted IPI (aaIPI) showed better accuracy and discriminatory ability. However, the models failed to identify a high-risk group with a 3-year overall survival rate below 40%. Our nomogram-based model demonstrated superior discriminatory ability and provided more precise individual predictions than all other models based on a risk stratification system. Most clinical prognostic models fail to accurately predict patient outcomes in patients over 60 years old. Therefore, nomogram-based models should be considered in this population to prevent information loss due to variable dichotomization.